POS1211 CHARACTERISTICS OF MYOCARDIAL INVOLVEMENT OF POLYMYOSITIS/DERMATOMYOSITIS EVALUATED BY CARDIAC MAGNETIC RESONANCE: A PILOT STUDY
Authors: S. Asatani, M. Tsukamoto, A. Yamada, H. Kobayashi, K. Sugito, Y. Okumura, H. Nakamura, N. Kitamura
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Polymyositis (PM) and dermatomyositis (DM) are autoimmune systemic diseases characterized by muscle weakness and inflammatory cell infiltration into skeletal muscle. Myocardial involvement is a common cause of death in PM/DM. It has been reported that myocardial involvement is observed in 9% to 72% of PM/DM [1], but it is still unclear. Electrocardiogram (ECG) and echocardiography are the most often used tests to evaluate cardiac abnormalities, but early detection of myocardial involvement in PM/DM is difficult. Cardiac magnetic resonance (CMR) is a noninvasive technique that has been efficiently evaluated in early myocarditis [2]. Late gadolinium enhancement (LGE) imaging evaluated at T1 remains one of the most important MRI techniques in the setting of suspected myocarditis [3], and the presence of LGE denotes tissue inflammation, necrosis, and early fibrosis [4,5]. Contrast-enhanced T1 mapping can calculate extracellular volume (ECV) fraction and is used for evaluation of myocardial fibrosis and scar [6]. T2 mapping is used for the evaluation of myocardial edema in association with myocardial inflammation [7]. T1, T2 and ECV are elevated in the setting of myocardial lesions. However, the evaluation of myocardial involvement in PM/DM by CMR still remains unclear and warrants investigation. <h3>Objectives</h3> This study aimed to investigate characteristics of myocardial involvement evaluated by CMR, and identify the clinical markers indicating the presence of cardiac complications in PM/DM. <h3>Methods</h3> PM/DM patients who visited our service between January 2014 to September 2022 were enrolled in this retrospective study. All patients met the 2017 EULAR/ACR classification criteria for idiopathic inflammatory myopathies, and patients with several elevated cardiac markers were included. Patients were excluded if they were complicated with other connective tissue diseases and cardiovascular diseases at the diagnosis of PM/DM. All patients performed ECG, echocardiography and CMR. Clinical and findings of CMR information were collected and statistically analyzed. The findings of CMR, such as T1, T2, LGE and ECV, were also analyzed. <h3>Results</h3> Twelve patients (3 patients with PM and 9 patients with DM) were enrolled in this study. ECG and echocardiography did not detect any abnormalities associated with PM/DM. However, in CMR, abnormalities indicating myocardial involvement were identified in 6 (3 patients with PM and 3 patients with DM) patients: 66.6% of patients had LGE, all patients had elevated ECV, and 33.3% of patients had elevated T2. Serum myoglobin levels were significantly elevated in patients with myocardial involvement (814.5±124.7 ng/mL vs 324.8±151.0 ng/mL, p=0.031). There were no significant differences in other cardiac markers, including serum CK, CK-MB and NT-pro-BNP, between with and without myocardial involvement. The following items were extracted as possible items for the presence of myocardial involvement: being PM (p=0.003) and anti-ARS antibodies positive (p=0.049). <h3>Conclusion</h3> Our results propose that myocardial involvement is more likely to develop in PM/DM patients even if the finding of echocardiography is normal. In addition, CMR should be performed in cases of PM/DM with high myoglobin levels, considering the possibility of myocardial involvement. <h3>References</h3> [1]Clin Cardiol. 2012;35:686 [2]Ann Rheum Dis. 2006;65:249 [3]Cardiothoracic Imaging. 2021;3:e210252 [4]J Am Coll Cardiol. 2009;53:1475 [5]Circulation. 2004;109:1250 [6]J Cardiovasc Magn Reson. 2012;14:54 [7]Br J Radiol. 2018;91:20170825. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.